1. Field of the Invention
This invention relates to a thin film magnetic head, a magnetic head device, a magnetic disk driving device and a method for manufacturing a thin film magnetic head.
2. Related Art Statement
A floating type thin film magnetic head to be used in a magnetic recording/reproducing device of a computer has at least one recording element and at least one reading element on the air outflow side of the slider thereof. As the recording element, an inductive type magnetic conversion type element is generally used, and as the reading, a magnetic conversion element using a magnetic resistive effect is used.
For realizing a high recording density in a magnetic disk using this kind of thin film magnetic head, it is required that data amount (surface recording density) to be restored in the unit area of the magnetic disk is enhanced. The surface recording density depends on the performance of the recording element, and can be enhanced by shortening the gap length between the recording poles of the recording element.
The surface recording density can be also enhanced by increasing the track number to be recorded in the magnetic disk. The track number recordable in the magnetic disk is normally represented as xe2x80x9cTPI (track per inch)xe2x80x9d. The TPI performance of the recording element can be enhanced by downsizing the recording head to determine the width of the data track. The size of the recording head is normally known as a track width.
However, the shortening of the gap length between the recording poles and the narrowing of the track width decrease the magnetic flux in between the recording poles, resulting in the degradation of the overwrite performance. Therefore, in view of recording performance, the shortening of the gap length and the narrowing of the track width can not employed for a high density recording magnetic disk having a high coercivity Hc.
To solve this problem, the recording pole structure, in which in a recording pole portion, a magnetic film having a high saturated magnetic flux density (a first magnetic film) is provided adjacent to a gap film and a second magnetic film having a smaller saturated magnetic flux density than the first magnetic film is provided on the first magnetic film, is suggested and practically used. For example, the specification of U.S. Pat. No. 5,606,478 discloses that the part of the recording pole portion adjacent to the gap film is made of a magnetic material having a higher saturated magnetic flux, for example Ni55Fe45, than the magnetic material having a NiFe composition which is usually used for the pole portion of the above thin film magnetic head.
In addition, the specification of Kokai Publication Kokai Hei 5-73839 (JP A 5-73839) discloses that an underfilm to plate a bottom magnetic core and a top magnetic core is made of a magnetic material having a higher saturated magnetic flux density than the magnetic materials constituting the bottom magnetic core and the top magnetic core.
The recording element composed of the inductive type magnetic conversion element generally has a first pole portion, a gap film, a coil film, an insulating film and a second pole portion. The first pole portion is composed of a magnetic film which extends backward from a medium opposing surface. The gap film is provided adjacent to the first pole portion, and the second pole portion is provided adjacent to the gap film. The second pole portion is composed of a magnetic film which extends backward from the medium opposing surface and joined with the magnetic film constituting the first magnetic pole portion at its rear portion. The coil film is embedded in the insulating film, and winds up vertically the joining portion of the first and second pole portions.
In a relatively primary type pole structure, the magnetic film extended from the second pole portion used to be, as a yoke portion, formed on the organic insulating material to support the coil film. The organic insulating film is inclined and rose up, between the pole portion and the yoke portion, at a given angle on the gap film. Therefore, the magnetic film to be formed on the organic insulating film is also inclined alongside the inclined portion at the given angle of the organic insulating film. The inclination starting point of the magnetic film is called as a xe2x80x9cThroat Height zero pointxe2x80x9d, and the inclination angle is called as a xe2x80x9cApex Anglexe2x80x9d. The magnetic film formed on the organic insulating film constitutes the second pole portion parallel to the gap film to the Throat Height zero point from its forefront in the air bearing surface, inclined at the Apex Angle from the Throat Height zero point, and continues to the yoke portion.
The throat Height zero point directly contributes to the electro-magnetic conversion characteristics of the recording element, so required to be controlled precisely. Moreover, the Apex Angle is required to be set to a small value so as not to be saturated magnetically for transmitting a magnetic flux generated from a writing current in the coil film effectively to the pole portion.
In the conventional pole structure in which the magnetic film extended from the second pole portion is formed on the organic insulating film, however, since the inclination starting point and inclination angle of the organic insulating film changes due to its applying process and baking process, it is difficult to control and set the Throat Height zero point. And the Apex Angle becomes relatively large.
The specifications of U.S. Pat. No. 5,606,478 and Kokai Publication Kokai Hei 5-73839 which are proposed as a high density recording means do not teach to decrease the Apex Angle.
For ironing out the above problem, for example, the specification of Kokai Publication Kokai Hei 7-225917 (JP A 7-225917) discloses that the second pole portion and its yoke portion are formed independently. In this case, since the rising start point of the yoke portion corresponds to the Throat Height zero point, the Throat Height zero point can be controlled and set high precisely.
However, the insulating film to support the coil film has its inclined surface. Therefore, the decreasing of the Apex Angle of the yoke portion continuing the second pole portion is restricted, so that the magnetic flux transmission efficiency for the pole portion and the overwrite characteristic can not be much improved.
Moreover, the specification of Kokai Publication Kokai Hei 7-267776 (JP A 267776) discloses that in the above pole structure in which the second pole portion and the yoke portion thereof are formed independently, the insulating film to support the coil film is flattened so that its surface can have the same level as that of the second pole portion, and the yoke portion to continue the second pole portion is formed on the flattened surface of the insulating film. In this case, since the edge portion of the second pole portion corresponds to the Throat Height zero point, the Throat Height zero point can be set precisely.
However, since the edge portion of the second pole portion is almost orthogonal to the gap film and the almost orthogonal angle for the gap film corresponds to the Apex Angle, the magnetic flux transmission efficiency for the pole portion and the overwrite characteristic can not be much improved.
Furthermore, Kokai publication Kokai Sho 60-193114 (JP A 60-193114) discloses that a depressed portion is formed on the surface of the slider substrate and a magnetic film continuing the first pole portion is formed in the depressed portion to manufacture a thin film magnetic head having a low step structure. In this case, however, it is difficult to control the Throat Height zero point precisely.
It is an object of the present invention to provide a thin film magnetic head having a recording pole structure of high recording performance.
It is another object of the present invention to provide a thin film magnetic head having a recording pole structure to be used for high density recording.
It is still another object of the present invention to provide a thin film magnetic head not to be saturated magnetically having excellent high frequency recording characteristics.
It is further object of the present invention to provide a thin film magnetic head having a small Apex Angle in which a Throat Height zero point can be controlled high precisely.
It is still further object of the present invention to provide a magnetic head device and a magnetic disk driving device using the above thin film magnetic head.
It is another object of the present invention to a manufacturing method suitable for the thin film magnetic head.
For achieving the above objects, a thin film magnetic head of the present invention includes a slider and at least one recording element. One surface of the slider constitutes a medium opposing surface. The recording element, formed on the slider, has a first pole portion, a gap film, a coil film, an insulating film and a second pole portion.
The first pole portion is composed of a magnetic film, extending backward from the medium opposing surface, and has a depressed portion. The depressed portion descends at a first inclination angle 01 from a first inclination starting point provided on the surface of the magnetic film backward from the first pole portion.
The insulating film is formed so as to embed the depressed portion and be located up to the upper side from the surface of the magnetic film, and then, has its inclined surface at least in the side of the medium opposing surface.
The gap film is adjacent to the first pole portion, and has its inclined portion alongside the inclined surface of the insulating film. The coil film is formed so as to be embedded into the insulating film.
The second pole portion has a first magnetic film and a second magnetic film. The first magnetic film, formed adjacent to the gap film, has a larger saturated magnetic flux density than the second magnetic film, and has its inclined portion of a second inclination angle xcex82 from a second inclination starting point. The second inclination starting point is located at the base portion of the inclined portion of the gap film.
The second magnetic film, adjacent to the first magnetic film and formed on the insulating film, extends backward from the medium opposing surface and, is joined with the magnetic film constituting the first pole portion.
In the thin film magnetic head of the present invention, the slider has the medium opposing surface, and the recording element is provided on the slider. Therefore, the air bearing generated in between the medium opposing surface of the slider and the medium by rotating the medium at a high velocity floats the slider, and in this condition, the medium can be magnetically recorded by the recording element.
In the recording element, the magnetic film continuing to the first pole portion extends backward from the medium opposing surface, and the gap film is provided adjacent to the first pole portion. Moreover, a first magnetic film included in the second pole portion is provided adjacent to the gap film. Moreover, a second magnetic film included in the second pole portion is adjacent to the first magnetic film, extending backward from the medium opposing surface, and is joined with the magnetic film constituting the first pole portion at its rear portion. The coil film is embedded into the insulating film.
This recording element can transmit the magnetic flux generated from the writing current in the coil film to the first pole portion and the second pole portion via the magnetic film constituting the first pole portion and the second magnetic film, and can generate a writing magnetic field at the gap film. The writing magnetic field enables the medium to be magnetically recorded.
The magnetic film continuing to the first pole portion has the depressed portion to constitute a low step structure which contributes to the decreasing of its Apex Angle. As mentioned above, although the low step structure having the depressed portion on the slider substrate is disclosed in Kokai Publication Kokai Sho 60-193114, the depressed portion is formed on the surface of the magnetic film continuing the first pole portion, not on the slider substrate in this invention. According to the low step structure of the present invention, the slider substrate has its flat surface, on which the magnetic film can be formed, so that the magnetic film can be easily formed and controlled in its film thickness.
The depressed portion is formed so as to descend at the first inclination angle xcex81 from the first inclination starting point provided on the surface of the magnetic film backward from the first pole portion. The first inclination angle xcex81 corresponds to the Apex Angle of the magnetic film continuing to the first pole portion, and thus, is set to a suitable value so that the magnetic film can not be saturated magnetically. The first inclination angle is preferably set to a value within 20 degrees to 60 degrees.
The insulating film to support the coil film is located up to the upper side from the surface of the magnetic film on which the depressed portion is formed, and has an inclined surface at least in the side of the medium opposing surface. The inclined surface of the insulating film contributes to the Apex Angle. In this case, since the insulating film is formed to be embedded in the depressed portion and thereby, the low step structure is already formed, the inclination angle of the inclined surface of the insulating film which contributes to the Apex Angle is decreased.
Of the first and second magnetic films in the second pole portion, the first magnetic film has a larger saturated magnetic flux density than the second magnetic film, and is provided adjacent to the gap film. In this case, even though the gap length between the recording poles and the track width are narrowed for realizing high density recording, the limited upper value of magnetic flux density to saturate the recording pole magnetically can be increased and thereby, the overwrite characteristic and recording performance thereof can be enhanced.
The first magnetic film has the inclined portion of the second inclination angle xcex82 from the second inclination starting point which is located at the base portion of the inclined portion of the gap film alongside the inclined surface of the insulating film. The second inclination starting point may be used for the Throat Height zero point of the first magnetic film. The second inclination angle xcex82 corresponds to the Apex Angle of the first magnetic film. Since the Apex Angle related with the magnetic saturation of the recording pole portion in the recording element is determined by the first magnetic film having a magnetic material having a large saturated magnetic flux density, the magnetic saturation is not more likely to occur in the recording pole portion. Therefore, the thin film magnetic head having a high recording performance can be obtained.
The second inclined angle xcex82 is set to a suitable value so that the second magnetic film continuing to the second pole portion may not be saturated magnetically. The second inclined angle xcex82 is preferably set to a value within 20 degrees to 60 degrees.
It is desired that the second inclination starting point is located nearer the side of the medium opposing surface than the first inclination starting point. In this case, the second inclination starting point corresponds to the Throat Height zero point. Since the first and second magnetic films constituting the second pole portion are formed after the magnetic film constituting the first pole portion, the Throat Height zero point can be determined higher precisely than the case that the first inclination starting point of the magnetic film constituting the first pole portion is used for the Throat Height zero point.
The other objects, constructions and advantages of the present invention will be described in detail, with reference to the attached drawings in the following embodiments.